1. Field of the Invention
The present invention relates to a method for manufacturing a chip inductor, and in particular to a method for manufacturing a surface mountable chip inductor used for electric appliances, etc.
2. Description of the Prior Art
A chip inductor is used for various electric appliances such as electronic home appliances as well electronic industrial equipment, etc. Recently, responsive to miniaturization and lightweight trends of various electric appliances, electric parts for electric appliances are also being miniaturized and rendered lighter. In the meantime, as a result of the development of digital communication, the frequency being used is gradually extended to a high frequency region, and accordingly, electromagnetic interference conditions have deteriorated. Most electronic devices are surface-mounted on a printed circuit board to automate fabrication processes. However, because the surface-mounted devices have a square shape, the conventional cylindrical inductor has difficulty in surface mounting.
An inductor is divided into a wire wound type and a stacked type, each having different application fields and fabrication methods.
In a wire wound type inductor, a coil is wound on a base body such as a magnetic material, etc. In this case, as the number of windings increases in order to get a high inductance, the high frequency characteristic deteriorates based on the increased number of windings, because a stray capacitance is present between the wound coils.
In the meantime, in a stacked type inductor, a base body is the same as the wire wound type inductor, but green sheets having internal electrodes printed as a spiral shape are stacked instead of a wound coil. Pressurization and sintering are performed on the stacked green sheets, and an external electrode is placed at both ends of the base body. The stacked type inductor is surface mounted on a circuit board and is used for noise elimination or impedance matching, etc., it is appropriate to for mass production and at the same time has an excellent high frequency characteristic by using Ag (silver) as an internal electrode. On the contrary, because the number of stacked green sheet is limited, there is a limitation on inductance, and particularly because a width of internal electrode is limited, there is a limitation in permitting sufficient current. Accordingly, it is inappropriate to use the stacked type inductor for power device, so its use is mainly limited for a low voltage and a low current. In addition, the fabrication process itself is very intricate and lots of equipment costs are required.
In order to solve above-mentioned problems, an inductor fabricated by forming a metal layer on a cylindrical body and forming a coil pattern on the metal layer by trimming of the metal layer has been presented, however surface mounting of the fabricated inductor is difficult because of its cylindrical shape. On the contrary, a square-shaped inductor is advantageous to surface mounting however a square-shaped inductor requires much time for trimming a metal layer on its surface using a laser, which causes fabrication costs to increase. In addition, variation in the quantity of laser light-interception prevents a pattern on the surface of the inductor from forming uniformly; accordingly its electric characteristic lowers.